| POLYMERS Vol.60 No.11 |
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COVER STORY
Crossover between Biophysics and Polymer Science |
| COVER STORY: Highlight Reviews |
| Protein Dynamics Revealed by Solution X-Ray Scattering and Molecular Dynamics Simulation | Mamoru SATO |
| <Abstract>
Recent development of protein crystallography allows us to understand protein
function at atomic level. However, protein is always in motion in solution,
which is of great importance to the function. Here, we show a novel method
using solution X-ray scattering (SXS) and molecular dynamics (MD) simulation
to characterize protein dynamics in solution. Keywords: SXS / SAXS / MD Simulation / Protein Dynamics / Intrinsically Disordered Protein |
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| Single Molecule Observation on the Folding Process of Proteins | Hiroyuki OIKAWA, Kiyoto KAMAGATA, and Satoshi TAKAHASHI |
| <Abstract> To understand the mechanism of protein folding, in which the conformational heterogeneity
of the unfolded protein is reduced drastically in a single kinetic step,
investigations at the single molecule level are necessary. The single
molecule fluorescence spectroscopy is one of the methods that have been
applied to protein folding. The structure and dynamics of the unfolded
state of proteins were revealed. In addition, the upper limit of the
transition path time, the time required for the transition from the unfolded
state to the folded state, was estimated to be 30 μs. The future prospect
of the single molecule method in protein folding study is briefly discussed
in this report. Keywords: Protein Folding / Single Molecule / Fluorescence Spectroscopy |
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| Lipids, Lipid Bilayers and Vesicles as Seen by Neutrons | Hideki SETO |
| <Abstract> Lipid
molecules self-assemble into bilayers in water with their hydrocarbon
chains facing inward due to their amphiphilic nature. The structural
and dynamical properties of lipids and lipid bilayers have been studied
by neutron scattering intensively. In this article, 3 topics are shown
as typical examples. 1) a time-resolved small-angle neutron scattering
on uni-lamellar vesicles composed of deuterated and protonated lipids
to determine lipid kinetics, 2) small-angle neutron scattering to investigate
spontaneous formation of nanopores on uni-lamellar vesicles, and 3) neutron
spin echo study to determine bending modulus of lipid bilayers. Keywords: Lipid / Lipid Bilayer / Multi-lamellar Vesicle / Uni-lamellar Vesicle / Nanopore Formation / Small-Angle Neutron Scattering / Neutron Spin Echo / Bending Modulus |
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| Fusion of Polymer Science and Biophysics by Molecular Simulations | Naohito URAKAMI and Takashi YAMAMOTO |
| <Abstract> Polymer
science and biophysics are expected to share many topics in their research
objects and methodologies. We here review computer simulation studies
of some of well-investigated biomolecules: silks, lipids, and proteins.
From the computational science point of view, we show that synthetic
and biological macromolecules have various common aspects, which can
lead to potential fusion of polymer science and molecular biophysics. Keywords: Computer Modeling / Molecular Simulation / Polymer Physics / Biophysics |
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| Characterization and Interaction Analysis of Proteins by Analytical Ultracentrifugation | Fumio ARISAKA |
| <Abstract> Analytical
Ultracentrifugation (AUC) was originally developed for the study of colloids
by Theodor Svedberg in the 1920's. However, due to the extraordinary
success in the application to proteins, AUC has long been utilized mainly
in the field of protein science. But recent emergence of the new type
of AUC, XL-A in 1991 and XL-I in 1996, together with remarkable developments
of analysis tools such as c(s) method, has prompted to re-attract scientists
in the field of polymer science including polysaccharide, colloids and
nano-particles such as carbon nano-tubes. Keywords: Analytical Ultracentrifuge / c(s) Method / Sedimentation Velocity / Sedimentation Equilibrium / Polysaccharide / Colloid / Nano-Particles |
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| Three-Dimensional Imaging of BiologicalMaterials with Electron Microscopy | Kuniaki NAGAYAMA |
| <Abstract> Electron
cryo-microscopy combined with a sample preparation technique of rapid
freezing, which is known to preserve the intact structure of biological
materials, begins to open a king's road toward the three-dimensional
structural analysis of biopolymers at an atomic resolution. Two approaches
of the single particle analysis and the electron tomography are introduced
together with examples recently reported and a new type of electron microscopy
recently invented in Japan, phase-contrast electron microscopy, is also
presented in the context to what extent the new stream is reinforced
in the near future. For readers to be able to effortlessly compare the
virtues of different techniques, only the structural analysis for viruses
has consistently been exemplified. Keywords: Electron Microscopy / Single Particle Analysis / Tomography / Phase Contrast |
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| Combining Sample Fractionation with MALS to Measure Mass and Size Distributions | Philip J. WYATT |
| <Abstract> Fractionating
samples comprised of polydisperse molecules by two distinct techniques
(size exclusion [SEC] and asymmetric flow field flow fractionation [A4F])
are compared and reviewed. Following such separations with measurements
at each elution element of concentration and multiangle light scattering
[MALS] permits the direct measurement of molar mass and size from which
the distributions of such components may be derived. The need to correct
for band broadening effects, especially with monodisperse constituents
such as proteins, is explained. Keywords: Light scattering / Field Flow Fractionation / SEC / A4F / Proteins / Branched Polymers / Band Broadening |
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| Front-Line Polymer Science |
| Innovative Smart Gels That Respond to Stimuli | Takashi MIYATA |
| <Abstract> Smart
gels that undergo changes in structures or properties in response to
environmental changes have many future applications as nanomaterials,
biomaterials, sustainable materials and so on. A variety of smart gels
exhibiting self-healing, shape-memory and stimuli-responsive properties
have been developed on the basis of unique concepts using molecular interaction.
The unique properties of smart gels can provide useful tools for constructing
innovative systems such as self-regulated drug delivery systems, sensor
systems, actuators and adaptive systems. Studies on smart gels not only
contribute significantly to the progress in fundamental polymer science,
but also lead to innovative science and technology. This article provides
an overview of innovative researches regarding smart gels and soft materials
that respond to environmental changes. Keywords: Gel / Hydrogel / Smart Gel / Stimuli-Responsive Gel / Self-Healing Material / Shape-Memory Material / Molecular Recognition / Molecular Complex / Molecular Interaction / Cross-Link |
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